Insect-borne disease is a major world health problem, accounting for nearly 20% of the total world- wide infectious disease burden. Many of these diseases are capable of spreading to the United States. Because insects depend on chemical senses for host location, feeding, and mating, a successful assault on insect disease vectors will benefit from understanding the molecular basis of insect olfaction. At least four separate proteins appear to be involved in insect pheromone detection: i) a pheromone-binding protein;ii) an odor-specific olfactory receptor (OR);iii) a co-OR that is expressed in most olfactory receptor neurons;and iv) sensory neuron membrane protein (SNMP), a member of the CD36 scavenger receptor family. Pheromone-binding proteins are water-soluble proteins;and OR, co-OR and SNMP are integral membrane proteins. Various lines of evidence support the hypothesis that the insect pheromone response results from the interaction of these four protein components. However, the three-dimensional structures of the integral membrane protein components are unknown, and it is not known whether these proteins undergo conformational changes during reception of olfactory signals. Also, little information is known about the nature of the interaction between the water-soluble and membrane-bound components. In the proposed experiments, luminescence resonance energy transfer (LRET) will be used to measure distances between defined sites on proteins involved in pheromone reception in the fruit fly, Drosophila melanogaster. The sites will be genetically inserted into the pheromone-specific receptor Or67d, the co-receptor Or83d, SNMP, and the pheromone-binding protein LUSH. After expression in Sf9 cells, luminescence measurements will provide information about the spatial arrangement of the receptor proteins and whether any conformational changes occur during pheromone reception. The results will help provide the basis for future development of methods to control insect vectors through manipulation of the olfactory system. PUBLIC HEALTH RELEVANCE: Insect-borne disease is a major world health problem, accounting for nearly 20% of the total world- wide infectious disease burden, with many of these diseases capable of spreading to the United States. Because insects depend on chemical senses for host location, feeding, and mating, a successful assault on insect disease vectors will benefit from understanding the molecular basis of insect olfaction. Also, one component of the insect pheromone receptor is similar to human proteins involved in atherosclerosis, inflammatory response, metabolic syndrome, cardiomyopathies, high frequency hearing loss, and Gaucher's disease.